Variable-diameter outer half pipe curved surface multi-point positioning clamping numerical control milling clamp

Abstract

The invention discloses a variable-diameter outer half tube curved surface multi-point positioning clamping numerical control milling clamp which is characterized by comprising a small-end positioning plate and a large-end positioning plate which are obliquely arranged, extension lines of the small-end positioning plate and the large-end positioning plate intersect to form a V shape, and the small-end positioning plate and the large-end positioning plate are both of a polygonal plate type structure. The shape of the polygonal structure is matched with the shape of the inner wall of the large end or the small end of the corresponding outer half pipe blank, and the small end positioning plate and the large end positioning plate are perpendicular to each other. A connecting plate is connected between the small-end supporting plate and the large-end supporting plate; a triangular reinforcing supporting plate is arranged above the connecting plate in parallel, the vertical reinforcing supporting plate is fixedly connected with a supporting plate adjusting column downwards, and the lower section of the supporting plate adjusting column is connected to the connecting plate in a threaded mode. Reinforcing supporting nails are arranged at the positions, located at the three vertexes, of the upper portion of the reinforcing supporting plate. The clamp solves the problems that in the prior art, a clamp is poor in inclusiveness of the size difference of outer bent pipes in the clamping process, and the positioning precision cannot be guaranteed.

Description

Technical Field

[0001] The present invention belongs to the technical field of aerospace machining, and particularly relates to a numerically controlled milling fixture for multi-point positioning and clamping of a variable-diameter outer semi-tube curved surface.

Background Art

[0002] In an aerospace liquid rocket engine, the gas outer bent pipe is a key load-bearing and flow-guiding component, and its machining accuracy directly affects the reliability and working performance of the engine. This type of part uses a superalloy material to meet the requirements of a harsh high-temperature and high-pressure service environment. Its blank is forged from a sheet material with a thickness of 17 mm. Affected by the forging process and heat treatment process, there are two major technical problems: on the one hand, the blank has low accuracy and poor consistency, lacks accurate features that can be directly used as positioning references, and the internal residual stress distribution of different batches of sheet materials is uneven due to differences in heat treatment states, resulting in a large deviation between the actual contour of the blank and the theoretical model; on the other hand, the thinnest part of the part is only 6 mm after machining, which belongs to a typical thin-walled and weak-rigid structure, and is prone to deformation during the machining process due to factors such as cutting force and vibration.

[0003] In the existing machining process, the clamping of semi-tube parts mainly relies on three profiling clamping plates for positioning. However, this clamping method has significant defects: firstly, it is difficult to adapt to the differences between the blank contour and the theoretical model, lacks compatibility with blanks deformed due to residual stress in different batches, and cannot guarantee the positioning accuracy; secondly, the clamping process requires repeated adjustment of the clamping plate position, which is time-consuming and laborious, and it is difficult to meet the positioning efficiency requirements of precision machining; thirdly, only relying on the force at the contact points of the clamping plate, the clamping force distribution is uneven, and the fixture is prone to looseness or the workpiece is prone to displacement during machining due to the action of cutting force, thereby affecting the machining accuracy of the curved surface and resulting in a high rejection rate and unqualified rate of the parts; it cannot meet the precision machining requirements of superalloy outer bent pipes in terms of positioning reference adaptability, clamping efficiency, and reliability.

Summary of the Invention

[0004] The purpose of the present invention is to provide a numerically controlled milling fixture for multi-point positioning and clamping of a variable-diameter outer semi-tube curved surface, so as to solve the problem that the existing fixture has poor tolerance for the size differences of outer bent pipes during the clamping process and cannot guarantee the positioning accuracy.

[0005] The present invention adopts the following technical solutions: A numerically controlled milling fixture for multi-point positioning and clamping of a variable-diameter outer semi-tube curved surface, based on an outer semi-tube blank, and the two ends of the outer semi-tube blank are divided into a large end and a small end according to the size of the opening;

[0006] The machining fixture includes:

[0007] The small end positioning plate and the large end positioning plate are arranged obliquely, and their extension lines intersect to form a V shape. Both the small end positioning plate and the large end positioning plate are polygonal plate structures, and the shape of the polygonal structure matches the inner wall shape of the large end or small end of the corresponding outer half-tube blank. The surfaces of the small end positioning plate and the large end positioning plate are perpendicular to each other.

[0008] The bottoms of the small end positioning plate and the large end positioning plate are connected to an H-shaped support frame, and the H-shaped support frame includes a small end support plate connected to the small end positioning plate and vertically arranged, and a large end support plate connected to the large end positioning plate and vertically arranged, and a connecting plate is connected between the small end support plate and the large end support plate;

[0009] A triangular reinforcing support plate is arranged parallel to the top of the connecting plate, and a support plate adjusting column is fixedly connected downwardly to the vertical reinforcing support plate, and the lower section of the support plate adjusting column is threadedly connected to the connecting plate; reinforcing support nails are arranged at the three vertices above the reinforcing support plate;

[0010] Among them, the support plate adjustment column is used to achieve up and down movement relative to the connecting plate through rotation, so as to drive the reinforced support plate to move up and down; each reinforced support nail is used to support the inner wall of the outer half-tube blank to play an auxiliary supporting role; the small end positioning plate is used to place the small end of the outer half-tube blank, and the small end positioning plate is parallel to the surface where the small end of the outer half-tube blank is located; the large end positioning plate is used to place the large end of the outer half-tube blank, and the large end positioning plate is parallel to the surface where the large end of the outer half-tube blank is located.

[0011] Furthermore, both sides of the bottom surface of the small end positioning plate are provided with small end adjustable clamping plates that can move along the tilting direction thereof, and the center of the bottom surface of the small end positioning plate is provided with a small end fixed clamping plate at the edge away from the large end positioning plate;

[0012] The two small-end adjustable clamps are used to clamp the inner walls on both sides of the small end of the outer half-tube blank, and the small-end fixed clamp is used to clamp the top inner wall of the small end of the outer half-tube blank.

[0013] Furthermore, each small-end adjustable clamp includes: a small-end adjustable support block, which is connected to the waist-shaped hole on the small-end positioning plate by bolts, and the extension direction of the waist-shaped hole is the same as the extension direction of the small-end positioning plate; it also includes a small-end adjustable support block pressure plate, which is detachably connected to the small-end adjustable support block by bolts, and is used to clamp the outer wall of the outer half-tube blank; the surfaces on the small-end support plate and the small-end adjustable support block that are in contact with the outer half-tube blank are both contoured surfaces of the theoretical model.

[0014] Further, the small-end fixed clamping plate includes a small-end fixed support block, which is fixedly connected to the center of the bottom surface of the small-end positioning plate away from the edge of the small-end positioning plate; it also includes a small-end fixed support block pressing plate, which is detachably connected to the small-end fixed support block by bolts and is used to clamp the outer wall of the semifinished outer half pipe blank; the surfaces of the small-end fixed support block pressing plate and the small-end fixed support block that contact the semifinished outer half pipe blank are both profiling surfaces of the theoretical model.

[0015] Further, on both sides of the bottom surface of the large-end positioning plate, there are large-end adjustable clamping plates that can move along its inclined direction, and at the center of the bottom surface of the large-end positioning plate away from the edge of the small-end positioning plate, there is a large-end fixed clamping plate;

[0016] The two large-end adjustable clamping plates are used to clamp the inner walls on both sides of the large end of the semifinished outer half pipe blank, and the large-end fixed clamping plate is used to clamp the inner wall at the top of the large end of the semifinished outer half pipe blank.

[0017] Further, each large-end adjustable clamping plate includes: a large-end adjustable support block with a C-shaped cross-section, which is arranged below the large-end positioning plate near the edge of the small-end positioning plate and has an opening facing outwards; it also includes an L-shaped large-end adjustable support block pressing plate, which is inserted into the large-end adjustable support block from the outside; the large-end adjustable support block pressing plate and the large-end adjustable support block form a mutually matching slider-rail structure; and both sides of the large-end adjustable support block pressing plate and the large-end adjustable support block are locked simultaneously by a long screw.

[0018] Further, the large-end fixed clamping plate includes a large-end fixed support block, which is fixedly connected to the center of the bottom surface of the large-end positioning plate away from the edge of the small-end positioning plate; it also includes a large-end fixed support block pressing plate, which is detachably connected to the large-end fixed support block by bolts, and the wall body of the semifinished outer half pipe blank is placed and clamped between the large-end fixed support block and the large-end fixed support block pressing plate; the surfaces of the large-end fixed support block pressing plate and the large-end fixed support block that contact the semifinished outer half pipe blank are profiling surfaces of the theoretical model.

[0019] Further, above the connecting plate, there is a cam connecting column mounting block, and a cam connecting column is arranged across the cam connecting column mounting block; the axial direction of the cam connecting column is perpendicular to the extending direction of the connecting plate, and cams are connected to both ends of the cam connecting column; the cams are used to rotate following the rotation of the cam connecting column to contact the side wall of the semifinished outer half pipe blank and complete the leveling of the semifinished outer half pipe blank.

[0020] Further, there are also two springs, and both ends of each spring are connected between the cam and the connecting plate.

[0021] Furthermore, the vertical reinforcement support plate is provided with a through hole, and a support plate positioning column is arranged through the through hole. The bottom of the support plate positioning column is fixed to the cam connection column mounting block; the support plate positioning column is used to guide the lifting of the reinforcement support plate.

[0022] The beneficial effects of the present invention are as follows: When machining the rough blank of the medium and large-sized free-form surface internal combustion gas elbow in the aerospace field, a variable-diameter outer half-tube curved surface multi-point positioning and clamping numerical control milling fixture of the present invention is used. At the large end and small end of the outer half-tube, the 0° reference line and the 90° reference line in the design drawing are marked and corresponded, and they are selected as the process reference lines. Referring to their positions, multi-point positioning of the outer half-tube rough blank is carried out, that is, multiple clamping blocks are used at both ends, a cam connected by a spring is used for floating positioning on the side, and a reinforcing support nail is used for internal auxiliary support at the top.

[0023] The present invention respectively demarcates the 0° reference line and the 90° reference line in the design drawing at the large end and small end of the outer half-tube rough blank, and constructs a spatial vertical reference plane with the large-end positioning plate and the small-end positioning plate arranged in an inverted V shape. The polygonal contours of the two positioning plates are completely shaped and matched with the inner wall of the rough blank end face, ensuring that the rough blank reference line is strictly aligned with the fixture positioning surface, directly establishing a processing reference consistent with the design coordinate system, and avoiding the cumulative error of traditional positioning reference conversion.

[0024] The adjustable clamping block groups at both ends are adapted to the dimensional differences of the rough blanks. Adjustable clamping block mechanisms are arranged on both sides of the large-end and small-end positioning plates. Combined with the shaped surface design, they dynamically adapt to the dimensional deviations of the forged and formed rough blanks caused by springback and thermal deformation. The clamping block pressing plate applies a pressing force perpendicular to the axis of the rough blank through bolts, and combined with the top constraint of the middle triangular plate, a composite positioning is formed. A spring-cam linkage mechanism is arranged above the connecting plate. The cam involute contour is used to contact the side wall of the rough blank, and a floating compensation amount is provided by the spring. This mechanism can offset the radial cutting force generated by uneven material removal in real time during the processing, and control the vibration amplitude of the workpiece. At the same time, the cam leveling function can quickly achieve the horizontal alignment of the rough blank, improving the processing efficiency.

[0025] The triangular reinforcement support plate realizes precise adjustment of the vertical height through the support plate adjustment column, and the reinforcement support nails distributed at the three vertices of its top support the inner curved surface of the rough blank. This support system forms a three-dimensional constraint with the positioning at both ends, effectively suppressing the machining deformation of large-span thin-walled parts. Especially in the processing of variable wall thickness structures, the displacement error of the workpiece is reduced. The triangular reinforcement support plate becomes the key component to solve the problems of "large span, weak rigidity, and easy deformation" in the machining of medium and large-sized elbows through triple designs of structural mechanics optimization, dynamic adaptive adjustment, and guiding positioning. Its innovation lies in the system integration with adjustable support nails, screw drive mechanisms, and guiding columns, forming a complete technical chain of "precision positioning - dynamic support - rigidity strengthening", providing a reliable process support for the precision machining of complex curved surface parts in the aerospace field.

Description of the Drawings

[0026] Figure 1 This is a schematic structural diagram of a numerical control milling fixture for multi-point positioning and clamping of a variable-diameter outer semi-tube curved surface according to the present invention;

[0027] Figure 2 This is a three-dimensional structural diagram of a numerical control milling fixture for multi-point positioning and clamping of a variable-diameter outer semi-tube curved surface according to the present invention;

[0028] Figure 3 This is a three-dimensional structural diagram of a numerical control milling fixture for multi-point positioning and clamping of a variable-diameter outer semi-tube curved surface according to the present invention from one perspective;

[0029] Figure 4 This is a three-dimensional structural diagram of a numerical control milling fixture for multi-point positioning and clamping of a variable-diameter outer semi-tube curved surface according to the present invention from another perspective;

[0030] Figure 5 This is a schematic diagram of the installation relationship between a numerical control milling fixture for multi-point positioning and clamping of a variable-diameter outer semi-tube curved surface according to the present invention and the outer semi-tube blank;

[0031] Figure 6 This is a perspective schematic diagram of the installation relationship between a numerical control milling fixture for multi-point positioning and clamping of a variable-diameter outer semi-tube curved surface according to the present invention and the outer semi-tube blank;

[0032] Figure 7 This is a schematic diagram of the reference line of the outer semi-tube blank of a numerical control milling fixture for multi-point positioning and clamping of a variable-diameter outer semi-tube curved surface according to the present invention.

[0033] Among them, 1. Reinforcing support pin, 2. Reinforcing support plate, 3. Support plate positioning column, 4. Small-end fixed support block pressing plate, 5. Small-end fixed support block, 6. Small-end adjustable support block, 7. Small-end adjustable support block pressing plate, 8. Small-end positioning plate, 9. Small-end support plate, 10. Base plate, 11. Spring, 12. Cam connecting column, 13. Cam, 14. Cam connecting column mounting block, 15. Connecting plate, 16. Support plate adjustment column, 17. Large-end support plate, 18. Large-end positioning plate, 19. Large-end adjustable support block, 20. Large-end adjustable support block pressing plate, 21. Large-end fixed support block, 22. Large-end fixed support block pressing plate, 23. Outer semi-tube blank.

Detailed implementation manner

[0034] The present invention will be described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0035] The gas bent pipe is used as the gas pipeline of the engine. The diameters at both ends are different. The end with the larger diameter is the large end, and the end with the smaller diameter is the small end. The plane where the large end is located and the plane where the small end is located are perpendicular to each other. The gas bent pipe blank is divided into two parts along its axis to obtain an outer semi-tube blank and an outer semi-tube blank. The processed outer semi-tubes are finally welded together to form an integral gas bent pipe.

[0036] For the outer half pipe, its bending radius is R, which is the radius of the circle where the intersecting edge of the outer half pipe and the outer half pipe is located. Based on the outer half pipe, the present invention proposes a variable-diameter outer half pipe curved surface multi-point positioning clamping numerical control milling fixture. Based on a blank 23 of the outer half pipe, the tooling of the present invention is dedicated to a specific pipe. Before designing the tooling, it will be matched and designed according to the various dimensions of the blank 23 of the outer half pipe.

[0037] As Figure 1 and Figure 2 shown, the machining fixture includes:

[0038] The small-end positioning plate 8 and the large-end positioning plate 18 which are inclined. The extension lines of the two intersect to form a V shape. Both the small-end positioning plate 8 and the large-end positioning plate 18 are of polygonal plate structures, and the shape of the polygonal structure matches the inner wall outer shape of the corresponding large end or small end of the outer half pipe blank 23. The planes where the small-end positioning plate 8 and the large-end positioning plate 18 are located are perpendicular to each other.

[0039] The distance between the small-end positioning plate 8 and the large-end positioning plate 18 is adjusted according to the bending radius R of the outer half pipe. For the selection of the distance, after the small end of the outer half pipe blank 23 is placed on the small-end positioning plate 8, the inclined plane where the small-end positioning plate 8 is located should coincide with the inclined plane where the 0° reference line of the theoretical model of the outer half pipe blank 23 is located. At the same time, the inclined plane where the large-end positioning plate 13 is located should coincide with the inclined plane where the 90° reference line of the theoretical model is located. Among them, the 0° reference line and the 90° reference line of the theoretical model of the outer half pipe blank are as Figure 7 shown. The 0° reference line is located at 20±1 mm near the small-end edge, and the 90° reference line is located at 20±1 mm near the large-end edge.

[0040] The bottoms of the small-end positioning plate 8 and the large-end positioning plate 18 are connected to an H-shaped support frame. The H-shaped support frame includes a small-end support plate 9 which is connected to the small-end positioning plate 8 and is vertically arranged, a large-end support plate 17 which is connected to the large-end positioning plate 18 and is vertically arranged, and a connecting plate 15 is connected between the small-end support plate 9 and the large-end support plate 17; the bottom of the H-shaped support frame is installed on the bottom plate 10.

[0041] A triangular reinforcing support plate 2 is arranged parallel to the top of the connecting plate 15, and a support plate adjustment column 16 is fixedly connected downwardly to the vertical reinforcing support plate 2, and the lower section of the support plate adjustment column 16 is threadedly connected to the connecting plate 15; reinforcing support nails 1 are arranged at the three vertices above the reinforcing support plate 2; the triangular support plate adopts a triangular frame structure, which naturally has excellent anti-bending and torsion properties, can effectively disperse cutting force and vibration impact, and reduce elastic deformation of thin-walled areas. The three reinforcing support nails are distributed in a triangular shape, forming three-point contact with the inner wall of the outer half-tube blank, providing uniform support force, avoiding local stress concentration, and improving the overall rigidity of the workpiece; the height-adjustable design is adapted to the height difference of different batches of blanks to ensure that the support position is always in the optimal state. Combined with the cam leveling mechanism and the spring buffer system, the triangular support plate can collaboratively complete the radial leveling and axial alignment of the blank, and adapt to the contour deviation of the blank caused by forging rebound.

[0042] The support plate adjustment column 16 is used to achieve up and down movement relative to the connecting plate 15 by rotation, so as to drive the strengthening support plate 2 to move up and down; Figure 6 As shown, each reinforcing support pin 1 is used to support the inner wall of the outer half-tube blank 23 to play an auxiliary supporting role; the small end positioning plate 8 is used to place the small end of the outer half-tube blank 23, and the small end positioning plate 8 is parallel to the surface where the small end of the outer half-tube blank 23 is located; the large end positioning plate 18 is used to place the large end of the outer half-tube blank 23, and the large end positioning plate 18 is parallel to the surface where the large end of the outer half-tube blank 23 is located. The vertical height adjustment of the reinforcing support plate 2 is realized, and the ±5mm height deviation caused by forging springback and thermal deformation of different batches of blanks can be dynamically adapted.

[0043] In some embodiments, Figure 3 As shown, both sides of the bottom surface of the small end positioning plate 8 are provided with small end adjustable clamping plates that can move along the tilting direction thereof, and a small end fixed clamping plate is provided at the edge of the bottom surface center of the small end positioning plate 8 away from the large end positioning plate 18; the two small end adjustable clamping plates are used to clamp the inner walls on both sides of the small end of the outer half pipe blank 23, and the small end fixed clamping plate is used to clamp the top inner wall of the small end of the outer half pipe blank 23. The adjustable clamping plates on both sides and the central fixed clamping plate form an "embracing" clamping structure, which disperses the cutting force to multiple points and avoids the stress concentration caused by traditional single-point clamping.

[0044] In some embodiments, Figure 3As shown, each small-end adjustable clamping plate includes: a small-end adjustable support block 6, which is bolted to the waist-shaped hole on the small-end positioning plate 8, and the extending direction of the waist-shaped hole is the same as that of the small-end positioning plate 8; by moving in the waist-shaped hole, for example, a stroke adjustment of ±5 mm can be achieved. It also includes a small-end adjustable support block pressing plate 7, which is detachably connected to the small-end adjustable support block 6 by bolts and is used to clamp the outer wall of the outer half-tube blank 23; the surfaces of the small-end support plate 9 and the small-end adjustable support block 6 that contact the outer half-tube blank 23 are both profiling surfaces of the theoretical model.

[0045] In some embodiments, as Figure 3 As shown, the small-end fixed clamping plate includes a small-end fixed support block 5, which is fixedly connected to the center of the bottom surface of the small-end positioning plate 8 away from the edge of the small-end positioning plate 8; it also includes a small-end fixed support block pressing plate 4, which is detachably connected to the small-end fixed support block 5 by bolts and is used to clamp the outer wall of the outer half-tube blank 23; the surfaces of the small-end fixed support block pressing plate 4 and the small-end fixed support block 5 that contact the outer half-tube blank 23 are both profiling surfaces of the theoretical model.

[0046] In some embodiments, as Figure 4 As shown, large-end adjustable clamping plates that can move along its inclined direction are arranged on both sides of the bottom surface of the large-end positioning plate 18, and a large-end fixed clamping plate is arranged at the center of the bottom surface of the large-end positioning plate 18 away from the edge of the small-end positioning plate 8;

[0047] The two large-end adjustable clamping plates are used to clamp the inner walls on both sides of the large end of the outer half-tube blank 23, and the large-end fixed clamping plate is used to clamp the inner wall at the top of the large end of the outer half-tube blank 23.

[0048] In some embodiments, as Figure 4As shown, each large-end adjustable clamping plate includes: a large-end adjustable support block 19, whose cross-section is C-shaped, which is arranged below the large-end positioning plate 18 near the edge of the small-end positioning plate 8 and has an opening facing outwards; it also includes an L-shaped large-end adjustable support block pressing plate 20, which is inserted into the inside of the large-end adjustable support block 19 from the outside inwards; the large-end adjustable support block pressing plate 20 and the large-end adjustable support block 19 are a mutually matching slider-rail structure; when the large-end adjustable support block pressing plate 20 is separated from the large-end adjustable support block 19, it is used to insert the outer half-tube blank 23; when the large-end adjustable support block pressing plate 20 and the large-end adjustable support block 19 are clamped, they are used to clamp the outer half-tube blank 23, and a long screw is used to lock the large-end adjustable support block pressing plates 20 on both sides and the large-end adjustable support block 19 at the same time. After the long bolt passes through the large-end adjustable support block pressing plate 20 and the large-end adjustable support block 19 on one side, it then extends to the large-end adjustable support block pressing plate 20 and the large-end adjustable support block 19 on the other side, simultaneously completing the locking of the two large-end adjustable clamping plates.

[0049] In some embodiments, as Figure 4 shown, the large-end fixed clamping plate includes a large-end fixed support block 21, and the large-end fixed support block 21 is fixedly connected to the center of the bottom surface of the large-end positioning plate 18 away from the edge of the small-end positioning plate 8; it also includes a large-end fixed support block pressing plate 22, and the large-end fixed support block pressing plate 22 is detachably connected to the large-end fixed support block 21 through bolts, and the wall body of the outer half-tube blank 23 is placed and clamped between the large-end fixed support block 21 and the large-end fixed support block pressing plate 22; the surfaces of the large-end fixed support block pressing plate 22 and the large-end fixed support block 21 that contact the outer half-tube blank 23 are profiling surfaces of the theoretical model.

[0050] In some embodiments, a cam connection column mounting block 14 is arranged above the connecting plate 15, and a cam connection column 12 is arranged across the cam connection column mounting block 14; the axial direction of the cam connection column 12 is perpendicular to the extending direction of the connecting plate 15, and cams 13 are connected to both ends of the cam connection column 12; the contour of the cam 13 is involute, and the cam 13 is used to rotate following the rotation of the cam connection column 12 to contact the side wall of the outer half-tube blank 23 and complete the leveling of the outer half-tube blank 23. As Figure 5 shown, when adjusted to make both sides contact the cam 13, the leveling of the outer half-tube blank 23 is achieved.

[0051] In some embodiments, two springs 11 are further included, and both ends of each spring 11 are connected to between the cam 13 and the connecting plate 15 through screws. Assist in aligning the blank and reduce the chatter between the cutting tool and the workpiece during machining.

[0052] In some embodiments, a through hole is provided in the vertical reinforcing support plate 2, and a support plate positioning column 3 is disposed through the through hole. The bottom of the support plate positioning column 3 is fixed to the cam connection column mounting block 14; the support plate positioning column 3 is used to guide the lifting of the reinforcing support plate 2.

[0053] In the present invention, the dimensions and positions of the various components of a variable-diameter outer semi-tube curved surface multi-point positioning and clamping numerical control milling fixture of the present invention are designed according to the precise dimensions of the pre-processed outer semi-tube. The processing fixture is manufactured according to this dimension. Then, the processing fixture is used to fix the outer semi-tube blank to be processed to complete subsequent precision numerical control machining.

[0054] A method for using a variable-diameter outer semi-tube curved surface multi-point positioning and clamping numerical control milling fixture of the present invention specifically includes the following content:

[0055] Refer to Figure 5 , first, the large-end support plate 17 and the small-end support plate 9 are positioned by pins and connected by screws, and are respectively installed at both ends of the bottom plate 10;

[0056] A connecting plate 15 is installed between the two end support plates, positioned by pins and connected by screws; the cam connection column mounting block 14 is installed on the connecting plate 15; the lower end of the support plate adjustment column 16 is threadedly connected to the connecting plate 15 for adjusting the vertical height of the reinforcing support plate 2. The reinforcing support nail 1 is installed on the reinforcing support plate 2, one at the front end and two symmetrically distributed at the rear end; the large-end positioning plate 18 and the small-end positioning plate 8 are respectively installed, positioned by pins and connected by screws; the corresponding large-end support plate 17, large-end adjustable support block 19, large-end adjustable support block pressing plate 20, large-end fixed support block 21, large-end fixed support block pressing plate 22 and screws are installed on the large-end positioning plate 18; the corresponding small-end support plate 9, small-end adjustable support block 6, small-end adjustable support block pressing plate 7, small-end fixed support block 5, small-end fixed support block pressing plate 4 and screws are installed on the small-end positioning plate 8; the cam connection column mounting block 14 is installed on the connecting plate 15; the cam connection column 12 is inserted into the circular hole in the cam connection column mounting block 14; cams 13 are installed on both sides of the cam connection column and leveled so that the two cams are aligned; the spring 11 is installed and the cam is tightened;

[0057] During use, assemble the fixture as described above. Fix the bottom plate 10 to the workbench of the numerical control machine tool by bolts, loosen the positioning block pressing plate screws and the locking screws of the adjustable positioning blocks. After placing the bent pipe blank at the corresponding position on the tooling, finely adjust the position. Refer to Figure 7 , align the 0° reference line of the outer semi-tube blank with the outer plane of the small-end positioning plate 8, and align the 90° reference line with the outer plane of the large-end positioning plate 18, and both cams 13 on both sides are in contact with the blank groove, realizing the horizontal alignment of the outer semi-tube blank 23;

[0058] Adjust the placement angle of the outer semi-tube blank 23 so that the inner walls at both ends thereof are respectively in contact with the profiling surfaces of the small-end fixed support block 5 and the large-end fixed support block 21;

[0059] Adjust the waist-shaped hole fixing screws of the small-end adjustable support block 6 and the large-end adjustable support block 19, slide each adjustable support block along the small-end positioning plate 8 and the large-end positioning plate 18 close to the inner wall of the outer semi-tube blank 23 so that it contacts the inner wall surface of the outer semi-tube blank 23; Rotate the thread pair of the adjustable support block, finely adjust its extension amount, lock the waist-shaped hole screws to ensure that each adjustable support block has no displacement; Then install the small-end adjustable support block pressing plate 7 and the large-end adjustable support block pressing plate 20 in sequence, and tighten the pressing plate screws so that both the small-end adjustable clamping plate and the large-end adjustable clamping plate can firmly fix the inner wall of the outer semi-tube blank 23; Then adjust and use the small-end fixed clamping plate and the large-end fixed clamping plate to respectively fix the inner wall of the outer semi-tube blank 23;

[0060] Rotate the support plate adjustment column 16, and drive the reinforcement support plate 2 to rise through screw drive until the three reinforcement support nails 1 contact the inner wall of the middle part of the blank;

[0061] Rotate the cam, and level the outer semi-tube blank 23 through the involute profile of the cam;

[0062] After fixing, perform machining. After the machining is completed, loosen the locking screws of the small-end adjustable clamping plate and the large-end adjustable clamping plate to quickly disassemble the parts.

[0063] When machining the medium and large-sized free-form surface type outer gas bend tube blanks in the aerospace field, the new type of CNC milling machine tooling fixture structure of the present invention is used, and a dual-reference positioning system is adopted to achieve high-precision long-span reference positioning ability through geometric constraints and adaptive adjustment, solving the problem of reference offset caused by the size fluctuation of the blank in the traditional fixture, effectively solving the problems of low machining efficiency and out-of-tolerance of the workpiece, and greatly shortening the machining cycle of the medium and large-sized outer semi-tubes.

[0064] The outer semi-tube tooling design of the present invention meets the requirements of adaptive precision machining, greatly improving the finish machining quality of the workpiece; The optimized tooling design simplifies the machining process flow, reduces the operation difficulty of the operator, and can be machined in place at one time on a five-axis precision CNC machine tool, reducing the machining cost.

[0065] The present invention sets a cam mechanism, adopts dynamic rigidity to enhance dynamic adjustment of the support in the middle area to suppress machining vibration, greatly improving the machining accuracy of the under-supported part of the large-curvature thin-walled part, and significantly reducing the machining chatter and tool breakage rate; The auxiliary device of the cam mechanism includes a cam connection column mounting block and a connecting plate, and through this auxiliary device, the rapid connection and rigidity strengthening of the fixture and the blank are realized.

[0066] The clamping structure of the fixture in the present invention is designed to fit the curvature of the model. The symmetric clamping design makes the pressure distribution uniform, avoiding machining deformation caused by local stress release. On the premise of facilitating loading and unloading, the overall structure design of the tooling fully meets the stiffness and strength requirements of machining.

Claims

1. A variable-diameter outer half-pipe curved surface multi-point positioning and clamping CNC milling fixture, characterized in that, Based on an outer semi-tube blank (23), both ends of the outer semi-tube blank (23) are divided into a large end and a small end according to the size of the opening; The processing fixture includes: The small-end positioning plate (8) and the large-end positioning plate (18) which are inclined, and the extension lines of the two intersect to form a V shape. Both the small-end positioning plate (8) and the large-end positioning plate (18) are of a polygonal plate structure, and the shape of the polygonal structure matches the inner wall shape of the corresponding large end or small end of the outer semi-tube blank (23). The planes where the small-end positioning plate (8) and the large-end positioning plate (18) are located are perpendicular to each other; The bottoms of the small-end positioning plate (8) and the large-end positioning plate (18) are connected to an H-shaped support frame. The H-shaped support frame includes a small-end support plate (9) which is connected to the small-end positioning plate (8) and is vertically arranged, and a large-end support plate (17) which is connected to the large-end positioning plate (18) and is vertically arranged. A connecting plate (15) is connected between the small-end support plate (9) and the large-end support plate (17); Above the connecting plate (15), a triangular reinforcing support plate (2) is arranged in parallel. A support plate adjusting column (16) is fixedly connected vertically downward to the reinforcing support plate (2), and the lower section of the support plate adjusting column (16) is threadedly connected to the connecting plate (15); At the three vertices above the reinforcing support plate (2), reinforcing support pins (1) are arranged; Among them, the support plate adjusting column (16) is used to realize the up and down movement relative to the connecting plate (15) by rotation, so as to drive the reinforcing support plate (2) to move up and down; Each of the reinforcing support pins (1) is used to support against the inner wall of the outer semi-tube blank (23) to play an auxiliary supporting role; The small-end positioning plate (8) is used to place the small end of the outer semi-tube blank (23), and the small-end positioning plate (8) is parallel to the plane where the small end of the outer semi-tube blank (23) is located; The large-end positioning plate (18) is used to place the large end of the outer semi-tube blank (23), and the large-end positioning plate (18) is parallel to the plane where the large end of the outer semi-tube blank (23) is located.

2. The multi-point positioning and clamping numerical control milling fixture for a variable-diameter outer semi-tube curved surface according to claim 1, wherein On both sides of the bottom surface of the small-end positioning plate (8), small-end adjustable clamping plates that can move along its inclined direction are arranged, and a small-end fixed clamping plate is arranged at the edge of the center of the bottom surface of the small-end positioning plate (8) far from the large-end positioning plate (18); Both of the two small-end adjustable clamping plates are used to clamp the inner walls on both sides of the small end of the outer semi-tube blank (23), and the small-end fixed clamping plate is used to clamp the inner wall at the top of the small end of the outer semi-tube blank (23).

3. The CNC milling fixture for multi-point positioning and clamping of a variable-diameter outer half-tube curved surface according to claim 2, wherein Each of the small-end adjustable clamping plates includes: a small-end adjustable support block (6), which is connected to the waist-shaped hole on the small-end positioning plate (8) by bolts, and the extending direction of the waist-shaped hole is the same as the extending direction of the small-end positioning plate (8); it also includes a small-end adjustable support block pressing plate (7), which is detachably connected to the small-end adjustable support block (6) by bolts and is used to clamp the outer wall of the outer half-pipe blank (23); the surfaces of the small-end support plate (9) and the small-end adjustable support block (6) that contact the outer half-pipe blank (23) are both profiling surfaces of the theoretical model.

4. The variable-diameter outer half-tube curved surface multi-point positioning and clamping numerical control milling fixture according to claim 3, wherein The small-end fixed clamping plate includes a small-end fixed support block (5), which is fixedly connected to the center of the bottom surface of the small-end positioning plate (8) away from the edge of the small-end positioning plate (8); it also includes a small-end fixed support block pressing plate (4), which is detachably connected to the small-end fixed support block (5) by bolts and is used to clamp the outer wall of the outer half-pipe blank (23); the surfaces of the small-end fixed support block pressing plate (4) and the small-end fixed support block (5) that contact the outer half-pipe blank (23) are both profiling surfaces of the theoretical model.

5. The variable-diameter outer semi-tube surface multi-point positioning and clamping numerical control milling fixture according to claim 1 or 2, characterized in that, On both sides of the bottom surface of the large-end positioning plate (18), there are large-end adjustable clamping plates that can move along its inclined direction, and at the center of the bottom surface of the large-end positioning plate (18) away from the edge of the small-end positioning plate (8), there is a large-end fixed clamping plate; The two large-end adjustable clamping plates are used to clamp the inner walls on both sides of the large end of the outer half-pipe blank (23), and the large-end fixed clamping plate is used to clamp the inner wall at the top of the large end of the outer half-pipe blank (23).

6. The CNC milling fixture for multi-point positioning and clamping of the variable-diameter outer half-tube curved surface according to claim 5, characterized in that, Each large-end adjustable clamping plate includes: a large-end adjustable support block (19), whose cross-section is C-shaped, which is arranged below the large-end positioning plate (18) near the edge of the small-end positioning plate (8) and has an opening facing outwards; it also includes an L-shaped large-end adjustable support block pressing plate (20), which is inserted into the large-end adjustable support block (19) from the outside inwards; the large-end adjustable support block pressing plate (20) and the large-end adjustable support block (19) form a mutually matching slider-rail structure; and the large-end adjustable support block pressing plates (20) on both sides and the large-end adjustable support block (19) are locked simultaneously by a long screw.

7. The variable-diameter outer half-tube curved surface multi-point positioning and clamping numerical control milling fixture according to claim 6, characterized in that, The large-end fixed clamping plate includes a large-end fixed support block (21), which is fixedly connected to the center of the bottom surface of the large-end positioning plate (18) away from the edge of the small-end positioning plate (8); it also includes a large-end fixed support block pressing plate (22), which is detachably connected to the large-end fixed support block (21) by bolts, and the wall body of the outer half-pipe blank (23) is placed and clamped between the large-end fixed support block (21) and the large-end fixed support block pressing plate (22); the surfaces of the large-end fixed support block pressing plate (22) and the large-end fixed support block (21) that contact the outer half-pipe blank (23) are profiling surfaces of the theoretical model.

8. A variable-diameter outer half-tube curved surface multi-point positioning and clamping numerical control milling fixture according to claim 1 or 2, characterized in that, Above the connecting plate (15), a cam connecting column mounting block (14) is provided, and a cam connecting column (12) is arranged through the cam connecting column mounting block (14); the axis direction of the cam connecting column (12) is perpendicular to the extending direction of the connecting plate (15), and cams (13) are connected to both ends of the cam connecting column (12); the cams (13) are used to rotate following the rotation of the cam connecting column (12) to contact the side wall of the outer half pipe blank (23) and complete the leveling of the outer half pipe blank (23).

9. The CNC milling fixture for multi-point positioning and clamping of a variable-diameter outer half-tube curved surface according to claim 8, wherein, It further includes two springs (11), and both ends of each spring (11) are connected between the cam and the connecting plate (15).

10. A variable-diameter outer half-tube curved surface multi-point positioning and clamping CNC milling fixture as described in claim 9, characterized in that, A through hole is provided perpendicular to the strengthening support plate (2), and a support plate positioning column (3) is arranged through the through hole. The bottom of the support plate positioning column (3) is fixed to the cam connecting column mounting block (14); the support plate positioning column (3) is used to guide the lifting of the strengthening support plate (2).

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